A representative, electric-powered, wheeled, automotive vehicle has an on-board electric motor whose motor torque output provides torque input to a drivetrain that includes driven wheels supporting the vehicle on a surface along which the vehicle travels. A known electric power source for the motor comprises an on-board compliment of D.C. batteries. The drivetrain delivers the torque to the driven wheels, thereby propelling the vehicle along the underlying surface.
A representative, engine-powered, wheeled, automotive vehicle has an internal combustion engine that provides torque input to the drivetrain, and that torque is transmitted through the drivetrain to the driven wheels that propel the vehicle.
An HEV is like an electric-powered vehicle in that torque output of an electric motor provides torque input to the drivetrain. It differs however in that it has an alternative power source for the electric motor, that is additional to an on-board compliment of D.C. batteries. That alternative power source comprises an internal combustion engine that drives an electric generator. As the engine runs, it operates the electric generator, and in turn, the generator delivers electricity to run the electric motor.
An HEV also has an electric control system that may include distinct, but inter-related, sub-systems for controlling operation of the electric motor, operation of the internal combustion engine, operation of the electric generator, and re-charging of the D.C. batteries. The control allows the options of operating the vehicle by use of D.C. battery power, or of operating the vehicle by running the engine to operate the electric generator. The engine may also operate the electric generator to re-charge the batteries.
A suitable electric motor is a traction motor. The electric motor may be a D.C. motor or an A.C. one. Likewise, for the generator. Depending on particular choices for the motor and generator, the electric control may include rectifiers and/or inverters for converting one form of electric power into the other.
An HEV may be similar to an internal-combustion-engine-powered automotive vehicle in having like control inputs available to the vehicle driver, including an accelerator control input, a service brake control input, and a parking brake control input, each of which can be operated by the driver independently of the others. Each control input includes an actuator such as a hand-operated pull or lever, or a foot-operated pedal. For example, depressing an accelerator pedal from an idle position accelerates the vehicle, depressing a service brake pedal applies the service brakes, and depressing a parking brake pedal, or pulling a parking brake handle, applies a parking brake.
The service brakes are typically fluid-power-operated, with each wheel having its own brake mechanism. The parking brake may be a mechanical, non-fluid-operated mechanism, or mechanisms, proximate a portion, or portions, of the drivetrain. Because of the independent operability of each of the three control inputs, it is possible that either one of the brakes may be applied while the accelerator pedal is being depressed.
"Two-toed" operation of the service brake pedal and the accelerator pedal may potentially damage, and/or shorten the life of, involved components. Applying the parking brake while the accelerator pedal is depressed would be considered undesirable for similar reasons. Having the accelerator pedal depressed as the parking brake is being released would also be considered undesirable.
In one respect, the present invention is directed to solutions for avoiding potential problems due to simultaneous operation of an accelerator and a brake in an HEV.
One general aspect of the invention relates to an automotive vehicle comprising: a drivetrain, including wheels for supporting the vehicle on a surface along which the vehicle is propelled; an on-board electric motor that, when operated, delivers torque output through the drivetrain to driven ones of the wheels for propelling the vehicle along such a surface; an on-board internal combustion engine; an on-board electric generator; an on-board D.C. power supply; an electric control system for controlling the electric motor, including the application of electric power input to the electric motor selectively from the generator and from the D.C. power supply respectively; an accelerator control input for requesting motor torque output from the electric motor; a service brake control input for selectively applying a service brake associated with one or more of the wheels; a parking brake control input for selectively applying a parking brake associated with the drivetrain; and an interface for interfacing the accelerator control input, the service brake control input, and the parking brake control input with the electric control system to control propulsion of the vehicle. The interface comprises a service brake interface portion for detecting application of the service brake by the service brake control input, a parking brake interface portion for detecting application of the parking brake by the parking brake control input, and an interface output portion for causing the electric control to operate the electric motor such that no motor torque output is delivered through the drivetrain from the motor when either brake interface portion detects application of the respective brake by the respective brake control input.
Another general aspect of the invention relates to an automotive vehicle comprising: a drivetrain, including wheels for supporting the vehicle on a surface along which the vehicle is propelled; an on-board electric motor that, when operated, delivers torque output through the drivetrain to driven ones of the wheels for propelling the vehicle along such a surface; an on-board internal combustion engine; an on-board electric generator; an on-board D.C. power supply; an electric control system for controlling the electric motor, including the application of electric power input to the electric motor selectively from the generator and from the D.C. power supply respectively; an accelerator control input for requesting motor torque output from the electric motor; a brake control input for selectively applying a brake associated with the drivetrain; and an interface for interfacing the accelerator control input and the brake control input with the electric control system to control propulsion of the vehicle. The interface comprises a brake interface portion for detecting application of the brake by the brake control input and an interface output portion for causing the electric control to operate the electric motor such that when the brake interface portion detects application of the brake by the brake control input, the motor torque output is rendered insufficient to cause propulsion of the vehicle along the surface.
Still another general aspect of the invention relates to a method of operating an automotive vehicle that has: a drivetrain, including wheels for supporting the vehicle on a surface along which the vehicle is propelled; an on-board electric motor that, when operated, delivers torque output through the drivetrain to driven ones of the wheels for propelling the vehicle along such a surface; an on-board internal combustion engine; an on-board electric generator; an on-board D.C. power supply; an electric control system for controlling the electric motor, including the application of electric power input to the electric motor selectively from the generator and from the D.C. power supply respectively; an accelerator control input for requesting motor torque output from the electric motor; a brake control input for selectively applying a brake associated with the drivetrain; and an interface for interfacing the accelerator control input and the brake control input with the electric control system to control propulsion of the vehicle, the interface comprising a brake interface portion for detecting application of the brake by the brake control input, and an interface output portion. The method comprises causing the electric control to operate the electric motor such that when the brake interface portion detects application of the brake by the brake control input, the motor torque output is rendered insufficient to cause propulsion of the vehicle along the surface.
More specific aspects of the invention will been set forth in the ensuing description, claims, and accompanying drawings.
The drawings, which will now be briefly described, are incorporated herein to illustrate a preferred embodiment of the invention and a best mode presently contemplated for carrying out the invention.